An Introduction to

ADO.Net
Contents
• What is ADO.Net?
• What happened to ADO?
• The ADO.Net object structure
• Connecting
• Commanding
• Readers and DataSets
What is ADO.Net?

• The data access classes for the

.Net framework
• Designed for highly efficient data
access
• Support for XML and disconnected
record sets
And the .Net framework?

• A standard cross language

interface
• Encapsulation of services, classes
and data types
• Uses XML for data representation
Where does ADO sit?
VB C# C++ Jscript …

Common Language Specification

Visual Studio .NET

ASP.Net Windows Forms

ADO.Net XML.Net

Base Class Library

Common Language Runtime (CLR)

Windows COM+ Services
What happened to ADO?

• ADO still exists.

• ADO is tightly coupled to client
server architectures
• Needs COM marshalling to pass
data between tiers
• Connections and locks are typically
persisted
ADO / ADO.Net Comparisons
Feature ADO ADO.Net
In memory Recordset object Dataset object
data storage single table Contains DataTables

Data Reads Sequential Sequential or non-

sequential

Data OLE/DB via the Managed provider

Sources Connection object calls the SQL APIs
ADO / ADO.Net Comparisons
Feature ADO ADO.Net
Disconnected Limited support, Strong support, with
data suitable for R/O updating

Passing COM marshalling DataSet support for

datasets XML passing

Scalability Limited Disconnected access

provides scalability
.NET Data Providers

SQL .NET

Data Provider
SQL SERVER

OLE DB .NET
Client Data Provider
OLE DB
Other DB
Provider

ODBC .NET ODBC

Data Provider Driver Other DB
Data Provider Functionality

Client .Net Data Provider

Connection Command
Rows
DataReader

DataSet
DataAdapter database
ADO.Net object model
Fill
DataAdapter DataSet
Update
UpdateCommand

DeleteCommand
SelectCommand

InsertCommand

Errors Collection

Command

Connection Parameters

Data Source
Namespaces

• System.Data &
System.Data.Common
• System.Data.SqlClient &
System.Data.OleDB
• System.Data.SqlTypes
• System.XML &
System.XML.Schema
Using Namespaces
• VB.Net
Imports System.Data
Imports System.Data.SqlClient
Dim sqlAdp as SqlDataAdapter
• C#
using System.Data;
using System.Data.SqlClient;
SqlDataAdapter sqlAdp= new
SqlDataAdapter();
SQL Namespace Objects
• using System.Data.SqlClient;
• SqlConnection
• SqlCommand
• SqlDataReader
• SqlDataAdapter
• SqlParameter
• SqlParameterCollection
• SqlError
• SqlErrorCollection
• SqlException
• SqlTransaction
• SqlDbType
Connecting to SQL
• using System.Data.SqlClient;

string sConnectionString =
"Initial Catalog=Northwind;
Data Source=localhost;
Integrated Security=SSPI;";

SqlDataAdapter sqlAdp= new

SqlDataAdapter(sConnectionString);

sqlAdp.Close();
sqlAdp.Dispose();
Connection Pooling
• ADO.Net pools connections.
When you close a connection it is released back into a
pool.
• SqlConnection conn = new SqlConnection();
conn.ConnectionString =
"Integrated Security=SSPI;Initial Catalog=northwind";
conn.Open(); // Pool A is created.
• SqlConnection conn = new SqlConnection();
conn.ConnectionString =
"Integrated Security=SSPI;Initial Catalog=pubs";
conn.Open();
// Pool B is created because the connection strings differ.
• SqlConnection conn = new SqlConnection();
conn.ConnectionString =
"Integrated Security=SSPI;Initial Catalog=northwind";
conn.Open(); // The connection string matches pool A.
Getting data

• SqlCommand
ExecuteReader
ExecuteNonQuery
ExecuteScalar
ExecuteXMLReader
• SqlDataAdapter
DataSet
Using the command object

• SqlCommand
Multiple constructors
• New()
• New(cmdText)
• New(cmdText, connection)
• New(cmdText, connection,
transaction)
Using the command object
• string sSelectQuery =
"SELECT * FROM Categories ORDER BY CategoryID";
string sConnectionString =
"Initial Catalog=Northwind;
Data Source=localhost;
Integrated Security=SSPI;";
SqlConnection objConnect = new SqlConnection(sConnectString);
SqlCommand objCommand = new SqlCommand(sSelectQuery,
objConnect);
/*
• objCommand.CommandTimeout = 15;
objCommand.CommandType = CommandType.Text;
• */

objConnect.Open();

SqlDataReader drResults;
drResults = objCommand.ExecuteReader()

drResults.Close();
objConnect.Dispose();
Command Methods

• .ExecuteReader() - Returns DataReader

• .ExecuteNonQuery() - Returns # of
Rows Affected

• .ExecuteXMLReader() - Returns
XMLReader Object to Read XML
documentation
• .ExecuteScaler() - Returns a Single
Value e.g. SQL SUM function.
The DataReader object

• DataReader objects are highly

optimised for fast, forward only
enumeration of data from a data
command
• A DataReader is not disconnected
The DataReader object

• Access to data is on a per record

basis.
• Forward only
• Read only
• Does support multiple recordsets
Creating a data reader
SqlDataReader sqlReader;
sqlReader =
sqlCommand.ExecuteReader();
while (sqlReader.Read())
{
// process, sqlReader("field")
}
sqlReader.Dispose();
Other Methods

• GetString(), GetInt() etc.

• GetSqlString(), GetSqlInt32() etc.
• GetValues()
• IsDBNull()
• GetSchemaTable()
DataSets
• In-memory representation of data
contained in a database/XML
• Operations are performed on the
DataSet, not the data source
• Can be created programmatically,
using a DataAdapter or XML
schema and document (or any
mixture)
Creating DataSets

• Setup SqlConnection
• Setup a SqlDataAdapter
• Create a DataSet
• Call the .Fill() method on the DA
DataAdapters

• Pipeline between DataSets and

data sources
• Geared towards functionality
rather than speed
• Disconnected by design
• Supports select, insert, delete,
update commands and methods
DataAdapters

• Must always specify a select

command
• All other commands can be
generated or specified
Using the DataAdapter
SQLDataAdapter sqlDA =
new SqlDataAdapter();

sqlDA.SelectCommand =
new SqlCommand ("select * from
authors“, sqlConnection);

DataSet sqlDS = new

DataSet("authorsTable");
sqlDA.Fill(sqlDS, "authorsTable");
DataAdapters

• For speed and efficiency you

should set your own
InsertCommand, UpdateCommand
and DeleteCommand
• Call GetChanges to seperates the
updates, adds and deletes since
the last sync. Then sync each
type.
DataTables

• A DataSet contains one or more

DataTables.
• Fields are held within the
DataTable.
• And in DataRows, DataColumns.
Sets, Tables and Rows

DataSet
DataTable
DataTable
DataRow
DataRow
Using DataTables

With a DataTable we can

• Insert, modify and update
• Search
• Apply views
• Compare
• Clear
• Clone and Copy
DataRelations

• New to ADO.Net
• Tables within a DataSet can now
have relationships, with integrity.
• Supports cascading updates and
deletes.
DataViews

• Like a SQL view

• Single, or multiple tables
• Normally used with GUI
applications via Data Binding.
References

• ADO.Net Programmer’s Reference

Bilbija, Dickenson et al.
Wrox Press
• http://oberon.idunno.org/sql/
• My email :
desai8@uwindsor.ca
Thank You!!